Effect of different surface finishing and of hydroxyapatite coatings on passive and corrosion current of Ti6Al4V alloy in simulated physiological solution.

Direct and alternating current electrochemical tests were carried out on Ti6Al4V with different surface finishing and with hydroxyapatite (HA) coatings. Sand-blasting and rough titanium deposits obtained by vacuum plasma spraying (VPS) bring about an increase of passive and corrosion current density (c.d.) with respect to smooth Ti6Al4V, as a consequence of the augmentation of the real surface. The presence of HA deposits obtained by VPS causes an increase of passive and corrosion c.d. of the metallic substrate of about one order of magnitude and this should be taken into account in view of human body applications.